Self-reversing scraper



July 11, 1967 w. F. WARD SELF-REVERSING SCRAPER 2 Sheets-Sheet l FiledSept. 20, 1965 INVENTOR WARREN F. WARD ATTORNEYS July 11, 1967 w. F.WARD 3,330,359

SELF-REVERSING SCRAPER med sept. zo, 1965 2 sheets-sheet 2 INVENTORWARREN F. WARD ATTORNEYS United States Patent Olice 3,333,359 PatentedJuly 11, 1967 3,330,359 SELF-REVERSING SCRAPER Warren F. Ward, 4419Rawling St., Dallas, Tex. 75219 Filed Sept. 20, 1965, Ser. No. 488,452Claims. (Cl. 166-175) ABSTRACT OF THE DISCLOSURE A migratory parathnscraper loosely surrounding a sucker rod and freely slidable in a tubingstring and having a body transversely divided into upper and lowerportions, each having at least one slot through its side wall throughwhich the sucker rod can be snapped into the central bore of the body,and the slots serving as iluid bypass passageways. An actuator rod isfixed in the lower body portion out of registry with its slot, or slots,and extends upwardly through a slot in the upper body portion and isbent to surround the sucker rod above the latter. The actuator holds theslots in the two body portions out of mutual registry. Detent means areprovided to releasably hold the body portions together when mated attheir transverse surfaces, thereby blocking the flow of uid through theslots and causing the scraper to rise on the sucker rod, but the detentmeans are released when the upper end of the actuator strikes anabutment on the sucker rod, thereby causing the body portions toseparate and permit ow of uid througth the slots, resulting in descentof the scraper portions on the sucker rod until the lower one strikes anabutment and the two portions re-mate.

This invention relates to self-cleaning oil well parain Scrapers of thetype which surround a sucker rod and migrate up and down substantiallythe entire length thereof as the well is pumped, and more particularlythe invention relates to the improvement of parain Scrapers by providinga novel valving action which automatically operates upon contact withthe sucker rod upsets to cause the scraper to rise when it reaches thebottom upset of the sucker rod and to fall when it reaches the topupset.

It is a principal object of this invention to provide a parain scrapercapable of migrating up and down a length of sucker rod as itreciprocates in a Well for the purpose of cleaning parain deposits notonly from the sucker rod but also from the adjacent tubing, thedirection of migration of the scraper being selectively determined bylautomatically-operated valve means cooperating with the downward eiectof gravity and with the upward etect of the rising column of uid in thetubing.

Another important object of the invention is to provide a novelparat-lin scraper combination including a scraper of the type showngenerally in Patents 2,604,364 and 2,793,917 and characterized by a bodywith a longitudinal slot through its side wall communicating with acentral bore receiving the sucker rod, and the present novel combinationfurther including valving structure for selectively opening and closingthe slot to alter the resistance of the scraper body to the upward ow ofiluid therepast, whereby when the valve means is closed the scraper bodywill present a large resistance to luid tlow causing it to rise in thetubing, and when the valve means is open the body will present a muchsmaller resistance to flow therepast thereby permitting the force ofgravity to cause it to descend in the tubing.

A further important object of the invention is to provide a novelscraper body divided transversely into two portions which have theirslots out of registry, so that liquid can pass through them when the twoportions are separated but is partly blocked from passing when the twoportions are moved together, this combination further including a tripmechanism passing through the slot in one portion of the body andextending longitudinally therebeyond to be fixed in the other portion ofthe body, so that when the scraper approaches one of the sucker rodupsets, the trip mechanism will contact the latter and will be shiftedlongtiudinally of said one portion of the body to change the axialposition of the other portion of the body with respect thereto andthereby reverse the direction of migration.

Since the present scraper depends upon gravity to cause it to dropdownwardly along the sucker rod when the valve means is opened, it isimportant that the scraper be heavy enough to drop despite the upwardlyflowing column of pumped fluid. It is also important that the openingprovided by the longitudinal slots in the two portions of the body belarge enough to by-pass the tiuid to make it possible for the scraper todrop. The scraper body portions can be made of metal, rubber, orplastic, such as nylon, although in the latter case it may be necessaryto add weight to the plastic body to help it fall in the tubing. Theoutside diameter of the body portions should be somewhat less than thetubing, and the axial bore therethrough should be somewhat greater indiameter than the sucker rod. Experiments on Working models have shownthat a body having a 3A central bore Works well on a 5/s" diametersucker rod. The width of the longitudinal slots should be great enoughnot only to -by-pass the well iluid how, but also great enough to permitthe insertion of the sucker rod into the bore through the slot byforcing it therethrough with a snapping action.

Another object of the invention is to provide novel yieldable detentmeans serving to hold the body portions together when they are mated inclosed position, the detent means in one embodiment comprising magnetmeans, and in another embodiment comprising a dart-shaped member mountedon an actuator rod which comprises part of the trip mechanism and themember being made of resilient material, such as rubber. This detentmember should be a wedging it in the slot Without being so tight as toprevent release therefrom when the trip mechanism is actuated against asucker-rod upset to drive the two body portions apart.

The edges of the body portions, particularly the edges of the slots,serve to scrape both the sucker rod and the tubing as the body portionstravel up and down therewithin. Moreover, there yare several phenomenawhich contribute to rapid rotation of the scraper during its travel,including the usual circular swirl of the fluid rising within thetubing. This rotation is augmented by tilting one or both slots out ofparallel relationship with the axis of the bores so that iiuid iiowthrough the slanted slots causes deection of the body portions,resulting in a circumferential component of force tending to maintainrotation. At vany rate, the scraper not only travels in a longitudinaldirection, it also rotates during this travel so that the edges of theslots act as paraihn cleaning blades slicing the soft paraiiin both fromthe inner walls of the tubing and from the outer surface of the suckerrod. The actuator rod extending through the slot in said one bodyportion is a very loose tit therein and tends to lash about duringmigration to clean the sides of the slot of paran deposits.

It is still another important object of the invention to provide amigratory, valved parain scraper which can be applied onto a standardsucker rod by merely snapping it into place, with the result that thereis no need to provide a special sucker rod wherein one of the ends hasno fixed upset structure as would be required in some prior artstructures to permit a fully cylindrical scraper to be introduced overthat end of the rod. The present structure can be snapped onto anystandard rod without any alteration of the rod.

The known prior art includes Patent 2,720,925 which shows a cylindricalmoving scraper structure which can be introduced over the end of asucker rod to be actuated by rod-engaging dogs along the length thereof.The mode of operation and the structure thereof is, of course, differentfrom the present invention. The prior art also includes variousgo-devils in the form of hollow torpedoes which can be introduced into apipeline, and some of which go-devils have valves which are manipulatedby the striking of a stop located inside of the pipeline, but none ofthese devices would be operative within a tubing string which also has asucker rod extending through its center. In general, the presentstructure operates most satisfactorily in wells in which the tubing isrelatively straight so that the sucker rods tend to maintain a centeredposition within the tubing. However, in wells where the bore is notstraight, the tendency of the sucker rod to lie against the tubing wallin an off-center position will interfere with free longitudinal movementof the present scrapper. This condition can be corrected in asatisfactory manner by mounting fixed scrapers on each end of the suckerrod, for instance Scrapers of the type shown in Patents 2,604,364,2,793,917, or others, these Scrapers serving the purpose of holding thesucker rod centered with respect to the tubing wall. Obviously, thepresent migratory Scrapers can operate between two fixed scrapers orbetween any other abntments which remain fixed to the sucker rod.Therefore, the operation of this migratory scraper is not limited toabutting against the upset at each end of the rod.

The present disclosure also includes novel specific structures forillustrating practical embodiments of the present invention, theseembodiments being described hereinafter in greater detail.

Other objects and advantages of the present invention will becomeapparent during the following discussion of the drawing, wherein:

FIG. l is a view in prespective showin-g a scraper according to thepresent invention descending on a sucker rod located within apump-tubing string, the tubing being broken away to show the scraperassembly approaching the upset at the lower end of the illustratedsucker rod;

FIG. 2 is an elevation view of the structure shown in FIG. 1, butshowing the scraper after it has contacted the upset and blocked theslots to provide a closed valving action, thereby causing the scraper torise within the tubing string;

FIG. 3 is an elevation view similar to FIG. 2, but taken at a locationnear the upper end of the sucker rod and showing the scraper assemblyabutted against the upper upset of the sucker rod, with the result thatthe body portions have again been separated to provide an open valvingaction through the slots, thereby adjusting the scraper assembly tocommence its descent;

FIG. 4 is a View of an actuatingrrod member;

FIG. 5 is a perspective view of the lower body portion which in theillustrative embodiment of the invention has its slot titled withrespect to the axis of its bore;

FIG. 6 is a perspective view of a detent means made of resilientmaterial of such width as to result in compression of the detent meanswhen inserted in the slot of the upper body portion;

FIG. 7 is an elevation view of a first modified form of scrapteraccording to the present invention; andV FIG. 8 is a perspective view ofa second modified form of scraper according to the present invention.

Referring now to the drawings, FIG. 1 shows a sucker rod R disposedwithin a length of pump tubing T, the latter being shown incross-section so as to illustrate a migratory parain scraper assemblyaccording to Ythe present invention located within the tubing. FIGS. 1,2, and 3 show the paran scraper assembly in pro-gressively differentpositions, as will be described hereinafter. The

sucker rod R is a standard rod having an upset U at each end locatedadjacent wrench flats W which are in trun located near threaded endportions, all of usual design.

The scraper assembly includes a scraper body divided into two portions 1and 2, and resembling a design which is generally well-known in theprior art and is characterized by substantially cylindrical bodyportions having bores 1a and 2a through the center thereof. Since it isnecessary that the body portions slide up and down on the sucker rod,the diameter of the bores 1a and 2a are made somewhat greater than thediameter of the sucker rod R between the upsets U. Likewise, the outsidediameters of the portions 1 and 2 are made less than the inside diameterof the tubing T so as to permit the body portions to freely migratewithin the tubing. The opposite ends of the body portions are chamferedas at 1b and 2b to prevent the body portion from snagging uponirregularities in the tubing. Both body portions have longitudinal slots1c and 2c extending through their side walls, the slots preferably,although not necessarily, being slightly Vnarrower in width than thediameter of the sucker rod R in the illustrated embodiment, whereby therod can be forced through the slots and Ventered into the bores 1a and2a with a snapping action. Either slot, or both slots, Vcan be tiltedout-of-parallel relationship with respect to the axis of the bores, andthe present illustrative embodiment shows the slot 2c tilted in thismanner. The two body portions mate with each other at transverse faces1d and 2d.

The migratory scraper assembly according to the present inventionincludes, in combination with the abovedescribed body portions, tripmeans for selectively opening or blocking the longitudinal passagewayprovided by the slots 1c and 2c, either separating or mating the twobody portions at the faces 1d and 2d as shown in FIGS. 1 and 2,respectively. The trip means includes an actuating rod member 3 having aright-angled lower end '3a and a. ring-shaped upper end 3b, as shown inFIG. 4. The. ringshaped upper end is C-shaped and therefore provides agap through which the sucker rod R can be passed so as to place theC-shaped portion 3b around the rod R as shown in FIGS. 1, 2, and 3. Theactuating member shown in FIG. 4 is further provided with a C-shapedmember 4 to which the angled lower end 3a is fixed, for example bywelding. The lower body member 2 is made of rubber, or plastic such asnylon, or some other dimensionally stable material, and the members 3aand 4 are embedded in the material as shown in FIG. 5 with the openingin the C-shaped member 4 in registry with the slot 2c of the bodyportion 2.

FIGS. 1, 2, 3, and 6 illustrate detent means 5 shaped to resemble a dartpoint and including a central portion 5a in front of a shank portion 5b.This detent means includes two side flukes 5c separated from the shankportion 5b at two undercut locations Sd which make it easier to compressthe two ukes 5c toward each other to narrow the width of the detentmeans 5 when it is inserted in the slot 1c. The detent means 5 ispreferably made of a resilient rubber or neoprene and has a bore 5e toreceive the rod 3 extending :above the lower body portion 2. Theresilient detent means is preferably bonded to the rod 3, and, withproper selection of materials, may even be molded integrally with thelower body portion 2. The actuating rod can be made of stainless steelrto provide adequate strength and resistance to corrosion.

After the member 3 is secured within the detent means 5 and the bodyportion 2, the latter can then be snapped onto the rod vi-a the slot 2c,and the looped upper end 3b Y of the actuating member 3 can be strainedopen enoughY to receive the sucker rod R. The actuating rodY 3 will thenpass longitudinally through the slot 1c as shown in FIGS. 1, 2, and 3.

FIG. 7 shows a first modified form of scraper 10 which performs in thesame general way as the scraper shown in FIG. 1. This modified scraperhas upper and lower body portions 11 and 12, respectively, includinglongitudinal slots 11c and 12e. The actuator rod member is the same asin FIG. 4, and is therefore similarly labeled with reference numerals 3and 4. 'Ihe detent means 15 is similar to that shown Iin FIG. 6, but ismodified to provide bulb-like projections 5p which mate withsimilarlyshaped grooves 1p near the lower end of the slot 1c when theupper and lower body portions are mated to provide an increased holdingpower for the detent means.

An additional feature of the modified form of FIG. 7 resides in theoutwardly extending ribs 16 molded into circumferential recesses 17 inthe upper body portion 11, which ribs are thin enough to be flexible,but stiff enough to provide improved Vwiping action as well as animproved sealing effect between the body portion 11 and the suckertubing T in which the scraper is intended to migrate.

FIG. 8 shows a second modified form of the invention in which thescraper 20 performs in a manner basically similar to the performance ofthe Scrapers shown in FIGS. 1 and 7, but in which the detent meanscomprises magnet means `rather than deformable dart-shaped members. Thissecond modification includes upper and lower body portions 21 and 22,respectively, having longitudinal slots 21C and 22C which are mutuallyout of alignment so that when the body portions are mated, the slots areblocked to restrict uid ow therethrough. The rod actuator 3, 4 servesthe same purpose as Iin the other illustrative forms of the invention.One of the body portions, portion 21 in the illustrative embodiment, hasone or more permanent magnets 23 embedded therein, and the other bodyportion, i.e., 22, has a permeable plate member 24 attached thereto. Theplate 24 can be bonded to the body 22 and/or Welded to the rod 3 to holdit in place.

It should be apparent that when the body portions 21 and 22 are united,the magnets 23 will hold the plate 24 with a releasable grip, which canbe :adjusted by suitable design so that the impact of the upper end 3bof the actuator against a sucker rod upset U will be sufiicient to breakthe magnetic grip at the end of the upstroke of the scraper 20, but sothat the lower portion 22 fwill not accidentally fall away from theupper portion 21 before such impact.

Referring again to FIGS. 1, 2, and 3, these three figures show asequence of events occurring during normal operation of the presentmigratory scraper assembly. In FIG. 1, the scraper is descending towardthe upset U at the lower end of the sucker rod R and counter to the flowof fluid travelling in the direction of the arrows F. The lower bodyportion 2 is separated from the upper portion 1 and is therefore in openposition so that the fiuid is free to travel upwardly through the slots1c and 2c to by-pass enough Huid to permit the assembly to gravitatedownwardly. As the assembly drops, eventually the bottom end of thelower body portion 2 will bottom against the upset U, and the bodyportion 1 will settle downwardly on the detent means 5 until thesurfaces 1d and 2d mate, thereby driving the detent means 5 into theslot 1c to assume the closed position shown in FIG. 2. The uidpassageway through the slots 1c and 2c are thus blocked respectively bythe body portion 2 and by the body portion 1, thereby greatly increasingthe resistance of the scraper to the flow of uid therepassed in thedirection of the arrow F, with the result that the whole scraperassembly becomes a piston which is buoyed up by the rising fluid F andforced to migrate upwardly on the sucker rod R, thereby scrapingparafiin from the outer surface thereof.

Eventually, the wire loop 3b of the actuating member 3 bottoms upon theupset U at the upper end of the sucker rod R as shown in FIG. 3, andupon further upward advance by the body 1, the detent means -5 isdislodged from the slot 1c and the body portions separate, therebyreopening the slot to the position shown in FIG. 1 to by-pass the fluidF through the slots and again re- 6 duce the buoyancy of the body 1sufficiently so that the force of gravity can cause it to drop until itreaches the lower upset U shown in FIG. l, 4at which time the valviug.action will again function to close the slots and to re-insert thedetent means 5 into the slot 1c.

As is well-known to those skilled in the art, the fluid Within thetubing T rotates during the pumping operation, and this has a tendencyto rotate the scraper so as to increase the paraffin scraping efficiencyby making the inside and outside edges of the slots 1c and 2c functionas paraffin scraping edges thereby improving the cleaning action of thebody both upon the sucker rod R and on the inner surfaces of the tubingT. Although the slots can be oriented parallel with the axis of thebores, a preferred structure of the body portions provides one or moreof the slots skewed slightly so that it is no longer parallel with saidaxis,- thereby adding a further rotative component.

The present invention is not to be limited to the exact forms shown inthe drawing, for obviously changes may be made therein within the scopeof the following claims.

I claim:

1. In oil well equipment, a parafn scraper assembly for migrating up anddown on a s-ucker rod having spaced abutments thereon and located withina surrounding tubing string, comprising:

(a) upper and lower body portions freely slidable Within said tubingstring and having longitudinal bores therethrough sized to freely passthe sucker rod, said portions having longitudinal slots in their sidewalls extending the full length of the body portion, and the adjacentends of the portions having matching transverse surfaces at which theycan mutually mate;

(b) means for maintaining the slots in the body portions out of mutualalignment;

(c) actuator means attached to one portion and extending beyond theother portion and operative to separate the body portions when theactuator means strikes an abutment; and

(d) detent means carried by said portions for yieldably holding theportions in mated relation.

2. In a scraper as set forth in claim 1, said actuator means comprisinga rod having one end fixed in the lower body portion and the other endterminating above the yupper body portion and partly surrounding thesucker rod.

3. In a scraper as set forth in claim 1, the slot in t-he lower bodyportion being skewed at an acute angle with respect to the axis of thebore therethrough.

4. In a scraper as set forth in claim 1, said actuator means comprisinga -rod having one end fixed in the lower body portion and extendingthrough the slot in the upper body portion, and said detent meanscomprising a resilient dart-shaped plug fixed to the lower portion atthe rod and resiliently distortable to frictionally grip said slot whenentered thereinto.

5. In a scraper as set forth in claim 1, said detent means comprisingmagnet means embedded in the body portions adjacent said transversesurfaces mutually attracting the portions when mated.

6. In oil Well equipment, a paraffin scraper assembly for migrating upand down on a sucker rod within a surrounding tubing string, comprising:

(a) upper and lower body portions freely slidable within said tubingstring and having longitudinal bores therethrough sized to freely passthe sucker rod, each portion having a longitudinal slot in its side wallextending radially into the bore and longitudinally the full length ofthe body portion, and the adjacent ends of the portions having matchingtransverse surfaces which they can mutually abut;

(b) actuator means fixed in one body portion, circumferentiallydisplaced from the associated slot of the one body portion, andextending longitudinally through the slot in the other body portion andterminating therebeyond and including means to prevent withdrawal of theactuator means from the last mentioned slot; said slots being out ofmutual alignment and Y (c) detent means carried by said body portionsand operative to releasably hold the body portions together when thelatter are abutted.

7. In a scraper as set forth in claim 6, said actuator means comprisinga rod having one end fixed in the lower body portion and the other endterminating above the upper body portion and partly surrounding thesucker rod and comprising said withdrawal preventing means.

8. In a scraper as set forth in claim 6, the slot in the lower -bodyportion being skewed at an acute angle with respect to the axis of thebore therethrough.

9. In a scraper as set forth in claim 6, said actuator means comprisinga rod having one end fixed in the lower body portion and extendingthrough the slot in the upper body portion, and said detent meanscomprising a resilient plug fixed to the lower portion at the rod andresiliently distortable to -frictionally grip said slot when enteredthereinto, the slot in the upper portion having recesses therein and theplug having protrusions shaped t yieldably lodge in the recesses. Y

10. In a scraper as set forth in claim 6, said body portions havingannular grooves in their outer surfaces, and having radially disposedfins in said grooves, the fins conforming with the peripheral shapes ofthe body portions, but extending therebeyond in radial directions.

11. In oil well equipment, a parafn scraper assembly for migrating upand down on a sucker rod within a surrounding tubing string, comprising:

(a) upper and lower body portions within the tubing string andsubstantially surrounding the sucker rod and sized to be freely slidablelongitudinally of both, the body portions being substantiallycylindrical and having longitudinal passageways in their sides forconducting well uids from one end of the scraper to the other, andhaving radially disposed adjacent end surfaces which block thepassageways when abutted;

o (b) actuator means fixed to one body portion and extending through apassageway in the other portion and therebyond, and disposed to maintainthe passage-` ways in the two portions out of mutual alignment;

' (c) means for limiting the longitudinal separation of the bodyportions; and

(d) means for yieldably maintaining the body portions in abuttingposition when the end surfaces are mated.

12. In a scraper as set forth in claim 11, said actuator meanscomprising a rod having one end iixed in the lower body portion and theother end terminating above the upper body portion and having anenlargement at said other end to prevent withdrawal of the rod from thepassageway.

13. In a scraper as set forth in claim 11, a passageway in one of thebody portions being skewed at an acute angle with respect to the axis ofthe Ibore therethrough.

14. In a scraper as set forth in claim 11, said actuator meanscomprising a rod having one end fixed in the lower body portion andextending through a passageway in the upper body portion, and saiddetent means comprising a resilient dart-shaped plug fixed to the lowerportion at the rod and resiliently distortable to frictionally grip saidpassageway when entered thereinto.

Y 15. In a scraper as set forth in claim 11, said detent meanscomprising vmagnet means embedded in the body Iportions adjacent saidtransverse surfaces mutually attract-v ing the portions when mated.

References lCited UNITED STATES PATENTS CHARLES E. OCONNELL, PrimaryExaminer.

JAMES A. LE-PPINK, Examiner.

1. IN OIL WELL EQUIPMENT, A PARAFFIN SCRAPER ASSEMBLY FOR MIGRATING UPAND DOWN ON A SUCKER ROD HAVING SPACED ABUTMENTS THEREON AND LOCATEDWITHIN A SURROUNDING TUBING STRING, COMPRISING: (A) UPPER AND LOWER BODYPORTIONS FREELY SLIDABLE WITHIN SAID TUBING STRING AND HAVINGLONGITUDINAL BORES THERETHROUGH SIZED TO FREELY PASS THE SUCKER ROD,SAID PORTIONS HAVING LONGITUDINAL SLOTS IN THEIR SIDE WALLS EXTENDINGTHE FULL LENGTH OF THE BODY PORTION, AND THE ADJACENT ENDS OF THEPORTIONS HAVING MATCHING TRANSVERSE SURFACES AT WHICH THEY CAN MUTUALLYMATE; (B) MEANS FOR MAINTAINING THE SLOTS IN THE BODY PORTIONS OUT OFMUTUAL ALIGNMENT; (C) ACTUATOR MEANS ATTACHED TO ONE PORTION ANDEXTENDING BEYOND THE OTHER PORTION AND OPERATIVE TO SEPARATE THE BODYPORTIONS WHEN THE ACTUATOR MEANS STRIKES AN ABUTMENT; AND